The longer excerpt where this quote came from is below. You can also read the full address of the Occasion of Christmas Greetings by Pope Benedict XVI on the Vatican site.
“Does man become himself by living for himself alone and only entering into relationships with others when he can break them off again at any time? Is lifelong commitment antithetical to freedom? Is commitment also worth suffering for? Man’s refusal to make any commitment – which is becoming increasingly widespread as a result of a false understanding of freedom and self-realization as well as the desire to escape suffering – means that man remains closed in on himself and keeps his ‘I’ ultimately for himself, without really rising above it. Yet only in self-giving does man find himself, and only by opening himself to the other, to others, to children, to the family, only by letting himself be changed through suffering, does he discover the breadth of his humanity. When such commitment is repudiated, the key figures of human existence likewise vanish: father, mother, child – essential elements of the experience of being human are lost.”—Pope Benedict XVI, Address on the Occasion of Christmas Greetings to the Roman Curia, December 21, 2012